The technology isn't anything new but, it's the context that makes it so uncomfortable.
People have very different "expectations" of privacy when they're having a conversation with an AI VS when they're browsing something like Facebook
Not to mention Facebook is free whereas you pay for a GPT subscription
ChatGPT is also freely available
I'm old enough to remember when people had expectations of privacy on Facebook, when the discovery that they didn't made for schocked headlines.